Having four or five times had an opportunity of bleeding people in the arm for trifling complaints, I have always received the blood in phials, filled with various gases, in a mode to be described hereafter. Venous blood agitated in nitrous oxide, compared with similar blood in common air, hydrogene, and nitrogene, was always darker and more purple than the first, and much brighter and more florid than the two last, which were not different in their color from venous blood, received between two surfaces of glass. It will be seen hereafter, that the coagulum of venous blood is rendered more purple when exposed to nitrous oxide, whilst the gas is absorbed; likewise that blood altered by nitrous oxide, is capable of being again rendered vermilion, by exposure to the air.
The appearances noticed in the above mentioned experiments, in the lungs of animals destroyed in nitrous oxide, are similar to those observed by Dr. Beddoes, in animals that had been made to breathe oxygene for a great length of time.
There were many reasons for supposing that the large purple spots in the lungs of animals destroyed in nitrous oxide, were owing to extravasation of venous blood from the capillary vessels; their coats being broken by the highly increased arterial action. To ascertain whether these phænomena existed at a period of the action of nitrous oxide, when the animal was recoverable by exposure to the atmosphere.
I introduced a rabbit of six months old, into a vessel of nitrous oxide, and after a minute, when it had fallen down apparently apoplectic, plunged him wholly under water; he immediately began to struggle, and what surprised me very much, died in less than a minute after submersion. On opening the thorax, the blood in the pulmonary veins was nearly of the color of that in animals that have been simply drowned. The lungs were here and there, marked with a few points; but there were no large purple spots, as in animals that have been wholly destroyed in nitrous oxide: the right side of the heart only contracted. In this experiment, the excitement from the action of the gas was probably carried to such an extent, as to produce indirect debility. There are reasons for supposing, that animals after having been excited to but a small extent by the respiration of nitrous oxide, will live under water for a greater length of time, than animals previously made to breathe common air.
V. Of the respiration of mixtures of Nitrous Oxide,
and other gases, by warm-blooded Animals.
a. A rabbit of near two months old, was introduced into a mixture of equal parts hydrogene and nitrous oxide through water. He immediately began to struggle; in a minute fell on his side; in three minutes gasped, and made long inspirations; and in four minutes and half, was dead. On dissection, he exhibited the same appearances as animals destroyed in nitrous oxide.
b. A large and strong mouse was introduced into a mixture of three parts hydrogene to one part nitrous oxide. He immediately began to struggle very much, in half a minute, became convulsed, and in about a minute, was quite dead.
c. Into a mixture of one oxygene, and three nitrous oxide, a small guinea-pig was introduced. He immediately began to struggle, and in two minutes reposed on his side, breathing very deeply. He made afterwards no violent muscular motion; but lived quietly for near fourteen minutes: at the end of which time, his legs were much convulsed. He was taken out, and recovered.
d. A mouse lived apparently without suffering, for near ten minutes, in a mixture of 1 atmospheric air, and 3 nitrous oxide, at the end of eleven minutes he began to struggle, and in thirteen minutes became much convulsed.
e. A cat of three months old, lived for seventeen minutes, in a very large quantity of a mixture of 1 atmospheric air, and 12 nitrous oxide. On her first introduction she was very much agitated and convulsed, in a minute and half she fell down as if apoplectic, and continued breathing very deeply during the remainder of the time, sometimes uttering very feeble cries. When taken out, she appeared almost inanimate, but on being laid before the fire, gradually began to breathe and move; being for some time, like most of the animals that have recovered after breathing nitrous oxide, convulsed on one side, and paralytic the other.